Improvement of the crystallinity and optical properties of sol-gel ZnO thin film by a PVD ZnO buffer layer

The effect of the ZnO homo-buffer layer on the structural, optical and electrical properties of the Sol-gel ZnO films was systematically investigated. The XRD and SEM results show that the homo-buffer layer can improve the degree of the preferential c-axis orientation (the best Lotering orientation factor (F) can reach 0.915), the grain size and the surface morphology of thereon ZnO films. A narrower UV emission at 380 nm was observed with weaker deep-level visible emission for the ZnO films with a homo-buffer layer using room-temperature (RT) photoluminescence (PL) spectra. The electrical results show that the carrier concentration of the films with buffer layer is decreased and the Hall mobility is increased, indicating that a ZnO homo-buffer layer can effectively improve the crystallinity of the films and improve both electrical and optical properties.